National Network of Regional Coastal Monitoring Programmes

Unique gravel beach dataset from Slapton Sands

Post by Kat Konstantinou, 28/05/2024, University of Plymouth, #gravelbeach

Slapton Sands is an embayed gravel barrier beach in south Devon. The site is exposed to a bi-directional wave climate with a dominant component from the south-southwest consisting primarily of Atlantic swell waves, and a secondary and less frequent component from the east (top panel). It exhibits typical rotational behaviour (bottom panel) in response to the current wave approach (Ruiz de Alegria-Arzaburu & Masselink, 2010), driven by the wave power balance between the primary storm directions (Wiggins et al., 2019). The beach also exhibits a long-term trend of eastward sediment transport and clockwise rotation clearly illustrated in the bottom figure panel. At interannual timescales, its behaviour is strongly linked to the North Atlantic Oscillation (NAO) and Western Europe Pressure Anomaly (WEPA) teleconnection patterns (Wiggins et al., 2020; Masselink et al., 2023). This unique dataset represents the only long-term (17 years), high-frequency (quasi monthly) dataset on gravel beaches at global scale and has provided valuable insights into gravel beach behaviour and helped unravel the mechanisms and processes driving beach changes over multiple timescales.

Top panel: Time series of significant wave heigh (Hs) measured by the Start Bay nearshore directional wave buoy operated by the South West Coastal Monitoring programme. The black solid line represents the 4-week moving average Hs. Storms (coloured circles) are identified as events during which Hs exceeded the 1% exceedance wave height and remained above the 5% exceedance wave height. Bubble colour indicates westerly (blue) and easterly (red) mean storm direction and bubble diameter is proportional to storm duration. Bottom panel: Beach volume time series for Slapton extracted at three profiles: at the southern end (p00; blue), in the middle (p15; black), and at the northern end (p18; red) of the beach derived from the CPRG monthly survey programme dataset (McCarroll et al., 2023).

Ruiz de Alegria-Arzaburu, A. R. & Masselink, G. (2010) 'Storm response and beach rotation on a gravel beach, Slapton Sands, UK'. Marine Geology, 278 (1-4), pp. 77-99. 10.1016/j.margeo.2010.09.004

Masselink, G., Castelle, B., Scott, T. & Konstantinou, A. (2023) 'Role of Atmospheric Indices in Describing Shoreline Variability Along the Atlantic Coast of Europe'. Geophysical Research Letters, 50 (22), pp. e2023GL106019.

McCarroll, R. J., Valiente, N. G., Wiggins, M., Scott, T. & Masselink, G. (2023) 'Coastal survey data for Perranporth Beach and Start Bay in southwest England (2006-2021)'. Scientific Data, 10 (1), pp. 17. 10.1038/s41597-023-02131-0

Wiggins, M., Scott, T., Masselink, G., McCarroll, R. J. & Russell, P. (2020) 'Predicting beach rotation using multiple atmospheric indices'. Marine Geology, 426 pp. 106207. 10.1016/j.margeo.2020.106207

Wiggins, M., Scott, T., Masselink, G., Russell, P. & McCarroll, R. J. (2019) 'Coastal embayment rotation: Response to extreme events and climate control, using full embayment surveys'. Geomorphology, 327 pp. 385-403. 10.1016/j.geomorph.2018.11.014